Archive for the ‘antenna’ Category
VHF NFD 2015
July 5th, 2015 | 
Author: The 2015 annual VHF national field day is now officially finished. So what’s the news?
Firstly I managed so excellent DX from the comfort of my own shack.
DX you say?
Yep 3 countries
Wow(?)…well yes they were EI,GM and GW so not exactly a long way but DX none the less.
Uhh?
Well yes, if the bands are normally silent and there’s not a station to be heard then the end of the village is DX.
But if there’s a bit of activity as there was this weekend then its always nice to work a few stations in other countries. But what would be really nice is to hear this level of activity on the bands regularly, and there to be rag chewing alongside contesting.
The ‘official entry’ from Workington was camped up on Corney Fell. I arrived too late to help get set up due to domestic duties but the photo’s didn’t do the conditions justice. There was a good 30+ mph wind up there and that 2m antenna was flapping about a lot. Hence the extra guy .
The VHF bands are XYL friendly in my house as the antenna’s are smaller, can be overlooked (on occasion) and
don’t warrant the usual response of ‘What the hell is that doing there?’ and ‘ How long do you intend on keeping that thing there?’ The answer to both of these questions is to mumble a bit and pretend to be busy doing something important.
So here’s a plea. Don’t make me take down this antenna, or worse still turn it vertically for FM. I’d quite like to work stations regularly on VHF SSB or even CW. Remember to switch the rig on, look for IO84 square and break the silence. A response to one contester today on 70cms was ‘That woke me up, I’ve been calling for 2 hours solidly and you’re the first one today’ isn’t good.
Big wheel antenna
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| Big Wheel for 2m |
A good 2m antenna for horizontal polarisation is the big wheel. Quite a few beacons use these as they require no rotator and a couple of these stacked give about 5dBd gain horizontally. So, these would be ideal for fixed station use. They would suit me well for UKAC 2m contests and general 2m SSB/CW use. I know that my 3 el, hand rotated, beam has about the same gain. One big wheel alone is better than a halo, but two suitably phased would be better than a small beam.
2 Meter Portable Ground Plane Gizmo Antenna
Portable, Ground Plane for 2 Meters made with BNC antennas
that you can ‘take down’
Its a compact ground plane antenna for portable use!
2 Meter Ground Plane Portable Gizmo Antenna in Operation 2
This antenna is built on a 2 inch washer. Holes were drilled in the washer to accommodate 4 radials. The center hole for the BNC to BNC connector was already there, but had to be reamed out. This (male to male) connector is where the coax from the radio is attached on the bottom of the washer. It also serves to hold (the center radiator element)!
(Note: The radiator, in the center, needs to attach to a BNC MALE connector, the cable from the radio also needs a BNC MALE connector. I used a male to male adapter for this purpose. It didn’t fit tightly so I used an old bike inner tube to cut a small spacer for taking up the slack. I’d have used a metal washer for ‘fitting’ the adapter, but I had already make 3 trips to the hardware store, so I used what I had)
Gizmo Portable Antenna
without the cover
Center Post of BNC Connector for the Radials are Shorted to the Shell Side
I used BNC female connectors from, Digikey, a good source for components! The center post of this connector is shorted to the ‘shell side’ to provide a ground plane with all the radials!
The 24 inch antennas from China were purchased on Ebay! CHEAP! The 2 inch washer is from the local hardware store. Everything fits on this washer, a 2 inch space, but the center coax is tedious to attach with all the radials in place, especially if you have big fingers.
The Cap is from a spice bottle!
I live alone so it was not a problem! LOL
Spice Bottle Cover
I love to use things for which they were never intended! This spice bottle cap is a good example of this. At this point, I’m not sure if I’ll seal it to the top BNC antenna radiator element or not? If I seal it (with hot glue, maybe) , the cap becomes permanently attached to the radiator element, and would be difficult if not impossible to remove. The whole idea here is to use this antenna as an impromptu portable antenna!
2 Meter Ground Plane Portable Gizmo Antenna Hanging from a Taped Tie Wrap
A tie wrap is used to ‘hang’ the antenna. Its hanging from a hook on my porch at the condo. I put 50 watts into it to get a repeater 10 miles away. SWR was 1:1 This is a portable antenna! Its not meant to be a permanent one. If you have ever needed a 2 meter antenna that you can pull up into a tree with a string or rope, this is it! Hauling it up 40 or 50 feet on a rope will get you better results than at ground level.
There is a joke that says, have you ever seen a golfer with only 1 club? Ham radio antennas are in the same category as golf clubs. You just can’t have too many!
All the elements can be removed for easy storage and transport, (radials as well as the vertical element)! I’m sure some clever ham will come up with a suitable case for this entire assembly. If I had one of those nifty clear plastic shipping tubes, I’d store in that! I’ll be on the lookout for one!
160m indoor loft antenna
Some years ago G6ALB and I wanted a simple talkback link that we could use when co-operating on experiments. We were 3km apart with Andrew being in the next village. We immediately thought about simple AM rigs for topband (160m).
As I had no 160m antenna, I built the design linked here. This antenna works well with best WSPR spots being over 1000km.
We decided that topband was too noisy for our simple AM rigs for our intended purpose. The noise floor at both our locations is very high on 160m. I have since moved QTH but we are still thinking about this link. We are now 3.3km apart. Probably 6m would be a better choice as less noisy and we both have vertical antennas.
See https://sites.google.com/site/g3xbmqrp3/antennas/160m_loft_ant .
Microvert antennas and similar
It looks like the Microvert antenna may have originated in Japan? The Microvert is a very compact antenna. Some believe the coax is a major part of the radiating system. Having never tried this sort of antenna I am unable to comment. This was posted to the Microvert Yahoo group earlier:
Whether you believe it’s the coax radiating or not, this is still interesting:
The Super Rad Antenna (Induced Secondary Radiation Antenna)
There are other websites about SRA (secondary radiation antenna), but unfortunately all in Japanese. Its definetly a Japanese thing!
I have all the parts required here to make one of these. Whether you believe its the coax radiating or not the results will be interesting.
Rob
M0RZFPS. My old 10m/12m modified microvert gives a good SWR.
Something that’s been bothering me
For a little while I’ve been pondering a problem on, or rather mostly off.
My SOTAbeams SB270 is a 2m & 70cm antenna that used a fairly unique way of holding the antenna elements. There are a set of elements for 2m and a set for 70cm. Each element had a hollow nylon cap head screw with a knurled end that was screwed into the plastic antenna boom. Unfortunately Richard can’t supply these as spares.
My SB270 is useful for, well SOTA, and the occasional VHF contest but what is makes up for in portability it lacks in gain. So I’ve thought about making a single boom version that covers 6m, 2m and 7ocm. The idea seems reasonable but the crucial aspect of mounting the antenna elements is a sticking point. Here’s a brief design brief.
1. Doesn’t need tools to assemble in the field
2. Must stay in place once installed
3. Must be easy to replicate (Just in case anyone else wants a go). So no need for specialist fabrication skills.
4. Must keep with the ‘elements live in the tube when not in use’ principle, So no big bulky parts
I have used standard pipe clamps and they get knocked about and blown around in our strong winds. Stauff type clamps need tools so they’re out. Some 3D printed parts are available on thingiverse but they look like they are for permanent installations or don’t really float my boat.
So, here’s the plea. Any ideas other than the one below?
The current thinking is to use some thicker walled ABS pipe (like durapipe which is cheap and easily found) and some threaded inserts for the parasitic elements. Only feeding the driven element is making me think a bit. May need a cut out or permanent part which has feeder and (ugly) balun.
Thinking caps on!
HF Mobile, A Different Kind of Radio Shack
The Scorpion Antenna is mounted in a good spot in the rear of my pickup truck bed. Seen here at Hagen’s Cove in Perry Florida on the Gulf of Mexico in the ‘big bend area’!
Going Mobile, Rag Chews, Nets, CW, its all available and very doable when you are on the road!
Mobile HF radio adds yet another dimension to Ham Radio. This is my second go, at HF Mobile operation.
Years ago, when ‘real life’ happened to me, I had no home QTH to operate from so I bought a new (at that time) Icom 706 M II G radio. It was a great choice. A DC to daylight rig, and its still working 15 years later. This next episode of HF mobile is greatly improved over my previous one. A good antenna at the time, was made by High Sierra. It was a screwdriver type. (the original mobile antenna’s were nick named ‘screwdriver’ because they used an electric screwdriver for moving the coil)
High Sierra no longer makes mobile antennas, but the good news is there is a good company making them in Arizona, Scorpion antennas!
The Scorpion antenna is a heavyweight, at 18 pounds and it needs a very robust base to hold it. Breedlove Mounts
Its the Rolls Royce of Mobile screwdriver type antennas, and not just because I bought one, it is indeed, a very rugged and carefully crafted antenna.
I’m primarily a CW op so I incorporated a touch sensitive paddle to do CW on the move or sitting still in a local park like this one at Hagen’s Cove, on the Gulf of Mexico in the ‘big bend area of Florida!’
The cap hat ‘whip’ is a 3 foot rod of solid aluminum. It shortens the overall whip. This is nice for parking my truck in the breezeway without hitting the roof.
A motorized coil is moved up or down electrically! Listening for the greatest noise, depending on the band of choice, puts me in the ball park for checking the SWR. A 1:1 ratio is easily obtainable if care is taken during installation. Bonding straps are a must. All the parts of the truck body, door, tailgate, hood, fenders and truck bed, must be bonded together to from a good RF ground. Not a DC ground, mind you, but an RF ground plane. (The ‘other half’ of the antenna’)
All the body parts of the truck must be bonded together with straps. RF flows on the surface not the cross section of a conductor, so the wider the better. Copper flashing best carries RF current but a compromise is make for braid due to continuous flexing while opening and closing doors, and tail gates.
Bonding is one of the things that separates a good installation from a poor one. I had fun with the first truck and radio set up back in 2001 but I learned a lot about mobile HF radio since then and did things differently this time.
Location, location, location! It sells real estate and its very important for HF Mobile Antennas!
What makes a good location on a vehicle?
I’ve seen many examples of HF radio antenna installations that work, but some work much better than others. Besides bonding, another good trick for a good installation is to use a very good location; the main mass of metal must be Directly under, not near, the base of the antenna. Will a bumper mounted antenna work? Yes, but one with a mass of metal directly beneath the antenna will work better.
Its simply a case of, more bang for the buck!
Positioning the bottom of the movable coil above the truck side wall is best.
The Scorpion antenna movable coil still has the protective bubble wrap on it in this picture.
Clearance is important!
The bottom of the coil must have clearance from metal objects like the side wall of the truck.
Detailed installation instructions come with the scorpion antenna. This is very important. A good installation will insure good operation. Skimping on installation will only hurt you in the long run.
I installed an auxiliary battery in the back set compartment of the truck. Its a sealed lead acid 75 Ah battery made by Optima. I bought it trough Apex Battery.
Optima Blue Top from Apex Battery co.
Optima Blue Top 75 Ah Auxilliary Battery
I can use either the auxiliary battery or the truck battery or both at the same time, thanks to a marine dual battery manual switch.
See its picture below.
I used #4 wire to connect the truck battery in parallel with the auxiliary battery in the back seat area. This large gauge wire greatly reduces voltage drop between the batteries. For extended stays in one place, I can operate on the auxiliary battery, without running the engine. This insures that the separated truck battery will start the truck when I’m done operating.
I have not yet mounted this switch on a back board, but that is coming. I need both hands to operate the switch now and I want to be able to do it with only one hand!
Dual Battery Switch in the -Both-Battery- Position
The business half of the IC 7100 is mounted to the floor of the truck on the hump. The battery box can be seen with a power pole connection box on top.
The control box for the IC 7100 rides up front on the center console as does the touch sensitive paddle. The microphone hands on the cup holder.
I have a Warren Gregoire headset for SSB. It features a noise cancelling microphone. Warren Gregoire Headset (no relation to me)
(Special note here; its illegal to have both ears covered with a headset in Florida while you drive.)
Its a stupid law because you can legally drive in Florida even if you are stone deaf! So that kills the reasoning for ‘listening to sirens’ on emergency vehicles!
Okay, that rant is done! Back to the Mobile installation.
Battery Box, with Power Pole Box,-top, IC 7100-bottom
AA1IK, Using Warren Gregoire Headset 2
Join me on a new Yahoo Group for HF Mobile ops.
New HF Mobile Yahoo Group
Here I am using the Warren Gregoire headset. This headset has a noise cancelling mic so its a good fit for mobile HF radio. SSB is a new thing for me. I’ve been a CW op, for most of my ham life. I’m having a great time meeting new folks all around Florida on 40 Meter SSB. Ham radio has lots to offer and I’m glad I have not yet exhausted all the possibilities. I have not forsaken CW, but SSB is a fun mode, as I’m sure many of you already know.
The IC 7100 is a two part radio. You saw the ‘business end’ in a previous photo. This photo shows the control head and the touch sensitive paddles Touch Sensitive Paddles They are held in place with a bungee cord. The black plate that you see here is a small plastic clipboard with the clip removed. It is glued in place to the light brown plate, and that is also a clipboard with the clip removed. Both clipboards are held in place with bungee cords. This allows me to remove the control head and the paddles for security reasons.
IC 7100 and Touch Paddles
Remote Switch-top, SWR/RF PWR Meter-left, Speaker-right
The remote switch for moving the antenna up and down to tune in each band is show in the little cubby hole. The SWR/PWR meter is stuffed into a hole where the ‘never has been used-ashtray’ was. The speaker is mounted just above the cup holder.
Remote Switch Moves Antenna Up and Down to Tune Each Band
This photo shows the remote switch. It is hand held, and easily put away after the antenna is tuned.
So! That is pretty much the end of a walk through in my new mobile ham radio shack. So far, I’ve listened to CW on the road but have not called CQ or talked to anyone while driving. I became interested in CW Mobile early in my ham radio career.
The first requirement for operating CW Mobile, according to an article that I read on the subject, said to ‘become a dynamite CW operator! Its been almost 25 years since then and I’m still working on that first requirement.
I’ll keep trying!
De AA1IK
Ernest Gregoire
